// SPDX-License-Identifier: GPL-2.0
/*
 * This file contains functions which manage high resolution tick
 * related events.
 *
 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 */
// SPDX-License-Identifier: GPL-2.0
/*
 * This file contains functions which manage high resolution tick
 * related events.
 *
 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 */
#include <errno.h>
#include <utils/err.h>
#include <seminix/cpu.h>
#include <seminix/smp.h>
#include <seminix/hrtimer.h>
#include "tick-internal.h"

/**
 * tick_program_event
 */
int tick_program_event(ktime_t expires, int force)
{
    struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);

    if (unlikely(expires == KTIME_MAX)) {
        /*
         * We don't need the clock event device any more, stop it.
         */
        clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
        dev->next_event = KTIME_MAX;
        return 0;
    }

    if (unlikely(clockevent_state_oneshot_stopped(dev))) {
        /*
         * We need the clock event again, configure it in ONESHOT mode
         * before using it.
         */
        clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
    }

    return clockevents_program_event(dev, expires, force);
}

/**
 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
 */
void tick_setup_oneshot(struct clock_event_device *newdev,
			void (*handler)(struct clock_event_device *),
			ktime_t next_event)
{
	newdev->event_handler = handler;
	clockevents_switch_state(newdev, CLOCK_EVT_STATE_ONESHOT);
	clockevents_program_event(newdev, next_event, true);
}

/**
 * tick_switch_to_oneshot - switch to oneshot mode
 */
int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
{
    struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
    struct clock_event_device *dev = td->evtdev;

    td->mode = TICKDEV_MODE_ONESHOT;
    dev->event_handler = handler;
    clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);

    return 0;
}

/**
 * tick_init_highres - switch to high resolution mode
 *
 * Called with interrupts disabled.
 */
int tick_init_highres(void)
{
    return tick_switch_to_oneshot(hrtimer_interrupt);
}

/**
 * tick_check_oneshot_mode - check whether the system is in oneshot mode
 *
 * returns 1 when either nohz or highres are enabled. otherwise 0.
 */
int tick_oneshot_mode_active(void)
{
    unsigned long flags;
    int ret;

    local_irq_save(flags);
    ret = __this_cpu_read(tick_cpu_device.mode) == TICKDEV_MODE_ONESHOT;
    local_irq_restore(flags);

    return ret;
}
